Department of Neurological Surgery, University of Utah, Salt Lake City, Utah.
Department of Neurological Surgery.
J Neurosurg. 2016 Nov;125(5):1217-1228. doi: 10.3171/2015.7.JNS15809. Epub 2016 Feb 5.
OBJECTIVE The optimal site for placement of tissue oxygen probes following traumatic brain injury (TBI) remains unresolved. The authors used a previously described swine model of focal TBI and studied brain tissue oxygen tension (PO) at the sites of contusion, proximal and distal to contusion, and in the contralateral hemisphere to determine the effect of probe location on PO and to assess the effects of physiological interventions on PO at these different sites. METHODS A controlled cortical impact device was used to generate a focal lesion in the right frontal lobe in 12 anesthetized swine. PO was measured using Licox brain tissue oxygen probes placed at the site of contusion, in pericontusional tissue (proximal probe), in the right parietal region (distal probe), and in the contralateral hemisphere. PO was measured during normoxia, hyperoxia, hypoventilation, and hyperventilation. RESULTS Physiological interventions led to expected changes, including a large increase in partial pressure of oxygen in arterial blood with hyperoxia, increased intracranial pressure (ICP) with hypoventilation, and decreased ICP with hyperventilation. Importantly, PO decreased substantially with proximity to the focal injury (contusion and proximal probes), and this difference was maintained at different levels of fraction of inspired oxygen and partial pressure of carbon dioxide in arterial blood. In the distal and contralateral probes, hypoventilation and hyperventilation were associated with expected increased and decreased PO values, respectively. However, in the contusion and proximal probes, these effects were diminished, consistent with loss of cerebrovascular CO reactivity at and near the injury site. Similarly, hyperoxia led to the expected rise in PO only in the distal and contralateral probes, with little or no effect in the proximal and contusion probes, respectively. CONCLUSIONS PO measurements are strongly influenced by the distance from the site of focal injury. Physiological alterations, including hyperoxia, hyperventilation, and hypoventilation substantially affect PO values distal to the site of injury but have little effect in and around the site of contusion. Clinical interpretations of brain tissue oxygen measurements should take into account the spatial relation of probe position to the site of injury. The decision of where to place a brain tissue oxygen probe in TBI patients should also take these factors into consideration.
创伤性脑损伤（TBI）后组织氧探头的最佳放置部位仍未解决。作者使用先前描述的猪局灶性 TBI 模型，研究了挫伤部位、挫伤部位近端和远端以及对侧半球的脑组织氧张力（PO），以确定探头位置对 PO 的影响，并评估生理干预对这些不同部位 PO 的影响。
使用受控皮质撞击装置在 12 只麻醉猪的右额叶产生局灶性损伤。使用 Licox 脑组织氧探头测量 PO，探头放置在挫伤部位、挫伤旁组织（近端探头）、右顶叶（远端探头）和对侧半球。在正常氧合、高氧、低通气和高通气下测量 PO。
生理干预导致了预期的变化，包括高氧时动脉血氧分压大幅升高、低通气时颅内压（ICP）升高、高通气时 ICP 降低。重要的是，PO 随与局灶损伤（挫伤和近端探头）的接近而显著降低，并且这种差异在动脉血中不同的吸入氧分数和二氧化碳分压水平下得以维持。在远端和对侧探头中，低通气和高通气分别与预期的 PO 值升高和降低相关。然而，在挫伤和近端探头中，这些效应减弱，与损伤部位和附近的脑血管 CO 反应性丧失一致。同样，高氧仅导致远端和对侧探头中预期的 PO 升高，而在近端和挫伤探头中几乎没有或没有影响。
PO 测量受距局灶性损伤部位的距离影响较大。生理改变，包括高氧、过度通气和低通气，严重影响损伤部位远端的 PO 值，但对损伤部位及其周围影响较小。脑氧测量的临床解释应考虑探头位置与损伤部位的空间关系。在 TBI 患者中放置脑组织氧探头的位置决策也应考虑这些因素。
